| The objective of this study was to identify and understand the chemical and physical factors that are important in the preparation of carbon-supported catalysts. For that purpose, efforts were made to critically evaluate and contrast theories and practices pertaining to diverse research disciplines dealing with carbon materials, and to illustrate how the rich surface properties of solid carbons can be best exploited to produce optimal catalysts. Extensive oxidative and/or thermal treatments were applied to batches of highly pure micro-, meso- and nonmicroporous carbons. Oxidative agents included HNO$sb3,$ $rm Hsb2Osb2$ and dry air. Treatment variables investigated systematically included temperature, reactant concentration and time of treatment. The aim was to provide predictive capabilities regarding both the quantity and the quality of oxygen complexes loaded on different structural types of solid carbons, in terms of experimentally measurable parameters. As a result, detailed guidelines were provided for the preparation of basic carbons, of acidic carbons, and of carbons with desirable functional group types or numbers.;Guidelines were also generated for the preparation of carbon-supported catalysts. Relatively unexplored experimental techniques were combined to provide a more scientific framework for their preparation. For illustration, two reactions were investigated: (i) carbon gasification, and (ii) hydrodesulphurization. In the former case, the concepts of structure sensitivity and of metal-support interactions were addressed quantitatively for the first time. A fractal relationship given by $rm TOFpropto Rsp{D{sb R-2}}$ (where D$sb{rm R}$ is an indicator of the reaction's (TOF's) sensitivity to the catalyst's structure, R) was found to be widely applicable to the study of (catalyzed) carbon gasification. Moreover, a link was found (via catalyst dispersion) between gasification and HDS activities of carbon-supported molybdenum catalysts. Thus, gasification experiments were used to guide the preparation of Mo/C catalysts. A careful systematic investigation of the influence of various oxygen functional groups on the adsorption and catalytic performance of Mo/C, Ni/C and Mo-Ni/C catalysts was performed. Methods were proposed for the screening or modification of potential carbon supports, and for balancing the seemingly opposite requirements of Mo and Ni ions in solution in order to produce optimal Mo-Ni/C bimetallic catalysts. |
